Microbial strains of importance for animal and human health are Campylobacter sp., Salmonella sp., Escherichia coli, moulds, etc. . . . As an example, Campylobacter is actually among world's most common human enteropathogens, causing campylobacteriosis. Campylobacteriosis is now the major zoonotic cause of human inflammatory intestinal infection, followed by salmonellosis and listeriosis. The clinical spectrum of enteric diseases due to Campylobacter infection ranges from generally mild non-inflammatory diarrhoea to severe inflammatory diarrhoea with faecal blood and leucocytes (Scott et al., 1997; Friedman et al., 2000; Oberhelman and Taylor, 2000).
The reported European incidence for human campylobacteriosis varies from 9.5 cases annually per 100,000 habitants in Spain to 108 cases annually per 100,000 in Scotland. The calculation may be underestimated since many cases are not reported and diagnostic tools vary in different countries. The incidence is still increasing in most European countries.
Campylobacter is also one of the most common bacterial causes of diarrhoeal illness in the United States. Virtually all cases occur as isolated, sporadic events, not as a part of large outbreaks. Active surveillance through US FoodNet indicates about 15 cases are diagnosed each year for each 100,000 persons. Many more cases go undiagnosed or unreported, and campylobacteriosis is estimated to affect over 1 million persons every year, or 0.5% of the general population.
In addition, Campylobacter infections are also linked to the Guillain-Barré Syndrome and arthritis (Scott et al., 1997; Nachamkin et al., 1998). The mortality associated with Campylobacter infections is relatively low and no specific treatment is required for the great majority of patients. Although Campylobacter doesn't commonly cause death, it has been estimated that approximately 100 persons with Campylobacter infections may die every year. However, Campylobacter infections are nevertheless serious problems because of high number of cases and their neurological symptoms, as well as the high social and economic costs of disease. The community pays a high economical cost due to loss of working hours, medical and treatment costs (mainly by use of fluoroquinolones and macrolides). Additionally, systemic infections do occur specially in elderly patients or in patients that are immunocompromised such as HIV-infected individuals. As the average lifetime of Europeans has been increasing consistently, one can expect more serious complications of Campylobacter infections particularly in cases involving old patients.
The problem with increasing or continued high incidence of human food-born infections cannot be solved on the basis of present knowledge. Maintaining increased hygiene standards have had an impact on salmonellosis but not on campylobacteriosis. Existing knowledge does not solve these problems, since there is lack of understanding the mechanisms by which zoonotic bacteria invade and infect (Scott et al., 1997; Oberhelman and Taylor, 2000; Newell and Nachamkin, 1992).
Outbreaks of campylobacteriosis are frequently traced to contaminated milk or water, whereas the most common cause of sporadic cases is eating undercooked meat, e.g. poultry. Contaminated chickens are, by far, the principal vehicles of infection (Friedman et al., 2000; Corry and Atabay, 2001; Newell and Wagenaar, 2000).
Poultry are a major reservoir of Campylobacter jejuni where the bacteria persist within the gastrointestinal tract. The epidemiology of C. jejuni in broiler flocks is still unclear. Generally, birds become infected about 3 weeks of age, but the sources and the routes of transmission of the microorganism to the broilers on the farm remain undetermined. Recently obtained data have indicated several sources of infection, including water, wild birds and farm personnel (Corry and Atabay, 2001). Once the microorganism is introduced in the flock, it spreads very rapidly leading to infection of almost all birds in a very short time. Although the reported level of Campylobacter in the chickens ceca varies between 105 and 1010/g, this massive colonisation does not induce any sign of the disease. The high amount of Campylobacter in the birds faeces causes further cross-contamination of Campylobacter-negative chicken carcasses in the processing plants. As a result, Campylobacter contaminates 50-80% of the raw chicken carcasses, depending on the geographical region where the study was conducted and the method used. This fact, in combination with the relatively low human infection dose can explain why eating undercooked poultry causes the majority of sporadic cases of campylobacteriosis. Therefore, one of the challenges is to understand how to block or diminish intestinal colonisation by Campylobacter in the host zoonotic animals, e.g. poultry.
Current methods of hygiene and bio-security used are improvement of the bio-security in the hatchery, a competitive exclusion technology or using chlorinated water (Corry and Atabay, 2001; Newell and Wagenaar, 2000). But they are insufficient to control or eliminate Campylobacter from the poultry food chain. Another strategy concerns preventive dosing of antibiotics (growth promoters) to the animals. However, concerns over potential health risk of antibiotic residues and resistant strains of pathogenic bacteria from animal sources have increased over the years and there are increasing pressures on the regulatory bodies to ban the use of these growth promoters (Barton, 1998; Dupont and Steele, 1987; Guillot, 1989; Prescott, 1997). Therefore, a total ban of antibiotics is foreseen for end 2005. Finally, another alternative approach for control of Campylobacter contamination can be active immunization of the birds. However, at the moment there is limited information about the function of the chicken immune system. Although some international research institutes are dealing with this topic, a real break-trough of this technique is for far future.
Therefore, alternative approaches for controlling food-born pathogens and other microbial contamination—in casu Campylobacter sp., Salmonella sp., Escherichia coli, etc. . . .—are urgently needed.
It is an object of the present invention to provide an alternative approach for controlling the amount and growth of food-born pathogens and other microbial contamination.
In particular, the present invention aims to provide compositions and methods for reducing the amount and/or growth of food-born pathogens and microbial organisms in consumable (edible) products. Another object of the invention is to provide compositions and methods for reducing the amount and/or growth of food-born pathogens and microbial organisms in animals or humans. The present invention is based on the use of specific medium chain fatty acids (MCFA) and in particular caproic acid (C6), caprylic acid (C8), and capric acid (C10), salts, derivatives or mixtures thereof, for the control of microbial contamination and growth.